Mobile service providers' infrastructure provides the access network for subscribers exchanging data with content companies. This puts mobile service providers in the position to offer useful services to content companies. Such services may fall in the following broad categories (1) maintaining meta-information about the subscribers and the subscriber access network; (2) offering access to network functions as service; and/or (3) offering infrastructure services to content providers. Mobile service providers maintain meta-information about the subscribers and the subscriber access network, which are useful to content providers to provide better services. Such information may be offered to content providers and includes, for example, subscriber identity, radio channel condition, subscriber geo-location, subscriber usage pattern etc. Mobile service providers may offer access to network functions as service to content provider. For example, if content companies need prioritized access to the mobile subscriber they can request the mobile service provider to “uplift” Quality of Service (QoS) settings for particular 5-tuple flows (i.e., data flows identified by source IP address, destination IP address, source port number, destination port number and the protocol) and have these 5-tuple flows mapped to specific, QoS improved, dedicated bearers maintained towards the mobile devices. Mobile service providers may offer infrastructure services to content providers and host content provider applications in the service provider infrastructure. These applications include, among others, data caches, video transcoders, ad insertion engine etc.
All these services require the content provider and the mobile service provider to exchange data related to the specific subscriber flows (data flow), which traverse both their networks. Several examples include: mobile service providers need to expose meta-information to content providers; content providers need to access an Application Programming Interface (API) exposed by mobile service providers to activate offered services; and content provider applications hosted in the service provider network may need to exchange data with their content providers and, therefore, the mobile service provider needs to provide a communication channel to enable this exchange. For example, if data flows are encrypted, a content server may need to provide the hosted applications with session encryption keys or Secure Sockets Layer (SSL) certificates. It is important that such data is exchanged in-band, i.e. embedded in the subscriber data flow they refer to. However, providing such data in-band can be challenging.